The accurate measurement of blood glucose concentration is important in the management of diabetes. Current methods of glucose monitoring involve piercing the skin and collecting blood samples for analysis up to four times daily or more. Even the non-invasive Glucowatch tm glucose monitoring system requires twice daily blood collection for calibration. This original, innovative invention will decrease and maintain the electrical resistance of the skin at a constant level. This allows for a controlled, increased passive or electroosmoticatly driven migration of glucose outwardly through the skin into a biosensor for analysis. By creating a constant permeability and avoiding a capacitance effect, we will be able to reproducibly extract and analyze glucose through the skin, minimizing the need for frequent calibration. Our long-term goal is to commercialize an iontophoretic device that will allow for the accurate and reproducible extraction of glucose from the skin or underlying subcutaneous space. Phase I research will study the linearity between glucose extraction and donor solution concentration in vitro and in vivo and demonstrate the advantage of our approach over the Glucowatch tm We will study glucose flux through human epidermis using a variety of protocols to optimize stratum corneum permeation enhancement and minimize intra- and inter-subject variability.